The present invention relates to a liquid-jet printing apparatus and a liquid container for performing printing on a print medium by discharging liquid and, more particularly, to a detection system which can detect whether or not an ink level in a liquid container reaches a predetermined level, liquid-jet printing apparatus using the detection system, liquid container used together with the system and apparatus, and a system of receiving changes in amount of light.
According to the conventionally known devices for detecting existence/non-existence of ink in an ink tank containing ink, electrodes are provided in the ink tank and electric conductivity between the electrodes is measured, or a discharged ink droplet is optically detected. Generally, a method of using electrodes complicates the structure of the ink tank. Thus, means for optically detecting existence/non-existence of ink is usually employed.
Particularly, a liquid-jet printing apparatus for performing printing by discharging liquid, generally comprises print means (printhead), an ink tank (liquid container), conveyance means for conveying a print medium and control means for controlling the above means. Herein, if ink left in the ink tank is lower than a predetermined amount, ink supplied to the printhead becomes insufficient and may cause discharge failure. For this reason, an apparatus for detecting a residual ink amount or existence/non-existence of ink in an ink tank has been suggested.
As ink-existence detection apparatus of this type, for instance, Japanese Patent Application Laid-Open (KOKAI) No. 8-112907 discloses an ink-jet printing apparatus which detects existence/non-existence of ink in an ink tank having a negative-pressure-generating member e.g. absorbent material, foaming material and the like, by transmitting light through a part of the transparent or semi-transparent wall surface of the ink tank and detecting changes in optical reflectance in the boundary portion between the wall surface of the ink tank and the negative-pressure-generating member.
Furthermore, U.S. Pat. No. 5,616,929 discloses an ink tank integrating an optical ink detection portion, formed with a light-transmitting material made of the same material as the ink tank, where the surface contacting ink has a predetermined angle with respect to a detection light path.
Moreover, in a case where an ink tank is detachable from a printing apparatus, the printing apparatus needs to automatically determine whether or not the ink tank is properly attached to the printing apparatus at the time of printing operation. For this, Japanese Patent Application Laid-Open (KOKAI) No. 9-174877 discloses a sensor system for detecting existence of an ink tank and ink of a predetermined level in the ink tank.
As described above, in the sensor system for detecting existence of an ink tank and ink level in the ink tank (or existence/non-existence of ink in the ink tank), it is desirable to share a detection sensor (light emission device and photoreceptor) so as to simplify the structure of the printing apparatus including the sensor system. Japanese Patent Application Laid-Open (KOKAI) No. 9-29989 discloses an ink-jet printing apparatus capable of detecting existence/non-existence of ink and existence/non-existence of an ink tank by a single photosensor.
Besides the above, Japanese Patent Application Laid-Open (KOKAI) No. 7-89090 is known as a detection apparatus for detecting liquid existence in a liquid container comprising: a negative-pressure generating member accommodating chamber accommodating a negative-pressure-generating member and having a liquid supply opening and atmospheric-air communicating portion; and a liquid containing chamber, which forms a substantially enclosed space, having a communicating portion connecting to the negative-pressure generating member accommodating chamber.
The use of the above-described sensor system is a reasonable approach in detecting existence/non-existence of an ink tank and ink of a predetermined level (or existence/non-existence of ink) in the ink tank with low cost.
However, since the above sensor system utilizes an optical sensor, it is preferable to satisfy the following requirements with low cost for more accurate detection, taking into consideration an expected life span of an optical device influenced by deterioration of a light emission device, a stained photoreceptor or the like, non-precise formation of the surface of a reflector, changes in an amount of light and so on in the surrounding environment.
The first requirement is to improve precision in detection by increasing an S/N (signal/noise) ratio. The second requirement is to accurately discriminate between the detection of existence/non-existence of an ink tank and the detection of ink of a predetermined level (or existence/non-existence of ink) in the ink tank when these are detected by a single sensor.
The present invention has been made in consideration of the above situation, and has as its first object to provide a practical detection system which can improve precision in detection by reducing noise received by a photoreceptor, liquid-jet printing apparatus using the detection system, and liquid container used together with the system and apparatus.
A second object of the present invention is to provide a liquid container which can accurately discriminate between the detection of existence/non-existence of a liquid container and the detection of a liquid level (or existence/non-existence of liquid) in the container when these are detected by a single sensor.
A third object of the present invention is to provide a detection system and liquid container which can improve precision in detection by reducing noise received by the photoreceptor, and which can accurately discriminate between the detection of existence/non-existence of a liquid container and the detection of a liquid level (or existence/non-existence of liquid) in the container when these are detected by a single sensor.
A fourth object of the present invention is to provide a liquid-jet printing apparatus which can accurately discriminate between the detection of existence/non-existence of a liquid container and the detection of a liquid level (or existence/non-existence of liquid) in the container when these are detected by a single sensor, even if the first requirement is not satisfied.
In order to attain the above first object, the detection system according to the present invention has the following configuration.
More specifically, the present invention provides a detection system comprising: optical means including a light emission unit for emitting light to a liquid container and a light receptor for receiving reflected light of the emitted light; a prism formed with light transmitting material, the prism having a surface constructing a part of an external wall surface of the liquid container and plural reflection surfaces, which are different from the surface, each being in contact with liquid and having a predetermined angle with respect to a light path of the emitted light; and determination means for determining whether or not the liquid in the liquid container exists based on the reflected light of the light emitted on the prism and received by the optical means, wherein the liquid container has a diffusion portion, provided in between a portion opposing to the light emission unit and another portion opposing to the light receptor of the prism, for diffusing light reflected on the external wall surface of the liquid container so as to prevent the reflected light from returning to the light receptor of the optical means.
Note that light in this present invention includes not only visible light but also infrared rays or the like.
Further note that it is preferable that the prism is provided on the bottom surface portion of the liquid container.
Furthermore, it is preferable that the diffusion portion is a concave polyhedral portion provided in the center of the bottom surface portion of the prism, or that the diffusion portion is a rough surface provided in the center of the bottom surface portion of the prism.
Moreover, it is preferable that the detection system further comprises a detection portion provided in the neighborhood of the prism, in cooperation with the optical and determination means, for when light is emitted by the optical means, determining whether or not the liquid container exist by reflecting a predetermined amount of light regardless of whether or not the liquid in the liquid container exists.
In this case, it is preferable that the detection portion is a concave curved surface portion provided on the external wall surface of the liquid container. Further, it is preferable that the amount of light, reflected on the detection portion, detected by the light receptor, is in between an amount of light reflected on the prism in a case where the liquid container contains liquid and an amount of light reflected on the prism in a case where the liquid container does not contain liquid. Moreover, it is preferable that the detection system further comprises a second diffusion portion, different from the diffusion portion, which is provided in between the prism and the detection portion, for diffusing light reflected on the external wall surface of the container, thereby preventing the reflected light from returning to the light receptor.
It is preferable that the determination means comprises: maximum value detection means for respectively obtaining maximum values of an amount of reflected light received when the liquid container and the optical means are within respective predetermined ranges; comparison means for comparing the maximum values detected by the maximum value detection means with respective predetermined threshold values; and discrimination means for discriminating whether or not the liquid in the liquid container exists and whether or not the liquid container exists, based on the comparison result obtained by the comparison means.
Furthermore, in order to attain the above first object, the liquid-jet printing apparatus according to the present invention has the following configuration.
More specifically, the present invention provides a liquid-jet printing apparatus comprising: a container holding portion capable of holding a liquid container which contains liquid; optical means, provided near the container holding portion, including a light emission unit for emitting light to the liquid container and a light receptor for receiving reflected light of the emitted light; and detection means for detecting whether or not liquid in the liquid container exists, based on the reflected light of the light emitted by the light emission unit and received by the light receptor, wherein the liquid container held by the container holding portion comprises: a prism formed with light transmitting material, the prism having a surface constructing a part of an external wall surface of the liquid container and plural reflection surfaces, which are different from the surface, each being in contact with liquid and having a predetermined angle with respect to a light path of the emitted light; and a diffusion portion provided in between the light reception portion and light reflecting portion of the prism, for diffusing light reflected on the external wall surface of the liquid container so as to prevent the reflected light from returning to the light receptor of the optical means.
Furthermore, in order to attain the above first object, the liquid container according to the present invention has the following configuration.
More specifically, the present invention provides a liquid container comprising: a liquid storage for reserving liquid; a liquid supply opening for supplying the liquid reserved in the liquid storage to an external; and a prism formed with light transmitting material, the prism having a surface constructing a part of an external wall surface of the liquid storage and plural reflection surfaces, which are different from the surface, each being in contact with liquid and having a predetermined angle with respect to a light path of emitted light, wherein the prism has a concave polyhedral portion constructed with plural surfaces having a different shape from that of the plural reflection surfaces of the prism, the concave polyhedral portion provided on the surface of the prism which constructs the external wall surface of the liquid container.
Note that it is preferable that the prism is provided on the bottom surface portion of the liquid container.
Furthermore, it is preferable that a concave depth of the concave polyhedral portion is about a thickness of an external wall surface whose part is constructed by the prism.
Moreover, it is preferable that a side surface of the prism partially contacts against a part of an external wall surface of the liquid container, and a notch is provided in the external wall surface which the side surface of the prism partially contacts against. Among the surfaces of the prism, which form a part of the external wall surface of the liquid container, it is preferable that at least one of the surfaces separated by the concave polyhedral portion has a convex surface. It is preferable that the internal surface of the concave portion of the concave polyhedral portion has a rough surface, or that the plural reflection surfaces of the prism have a smooth surface and the side surface of the prism has a rough surface so as to irregularly reflect light.
Furthermore, it is preferable that the liquid container further comprises a detection portion provided in the neighborhood of the prism, when light is emitted by external optical means, for reflecting a predetermined amount of light regardless of whether or not the liquid exists in the liquid container. In this case, it is preferable that the detection portion is a concave surface portion provided on the external wall surface of the liquid container, and that a diffusion portion is further provided in between the prism and the detection portion, for diffusing light reflected on the external wall surface of the liquid container, thereby preventing the reflected light from returning to a light receptor of the external optical means.
Moreover, in order to attain the aforementioned first object, a light amount change receiving system according to the present invention has the following configuration.
More specifically, the present invention provides a light amount change receiving system for emitting light on a prism and receiving reflected light of the emitted light, the prism formed with light transmitting material, having a surface constructing a part of an external wall surface of a container and plural reflection surfaces, which are different from the surface, each being contact with contents of the container and having a-predetermined angle with respect to a light path of the emitted light, comprising: a diffusion portion, provided in between a light incident portion of the prism for receiving the light emitted from light emission means and a light reflecting portion, of the prism, for reflecting the light intended to return to light reception means, for diffusing light reflected on an external wall surface of the container, thereby preventing the light from returning to the light reception means.
Further, in order to attain the aforementioned first object, a liquid container according to the present invention has the following configuration.
More specifically, the present invention provides a liquid container attachable/detachable to/from a printing apparatus having optical means in which a light emission unit and a light receptor are fixed with a predetermined space, the liquid container being movable relative to the optical means, comprising: a prism formed with light transmitting material, having a surface constructing a part of an external wall surface of the liquid container and plural reflection surfaces, which are different from the surface, each being in contact with liquid and having a predetermined angle with respect to a light path of light; and a diffusion portion provided on a surface of the prism constructing a part of an external wall surface of the liquid container, for diffusing light reflected on an external wall surface of the container, thereby preventing the light from returning to the light receptor, wherein the diffusion portion is provided in between a light incident portion of the prism for receiving light from the light emission portion and a light reflecting portion of the prism for reflecting the light intended to return to the light receptor.
Herein, it is preferable that the liquid container further comprises: a negative-pressure generating member accommodating chamber, accommodating a negative-pressure-generating member and having a liquid supply opening and an atmospheric-air communicating portion; and a liquid storage, having a passage opening connected to the negative-pressure generating member accommodating chamber and forming a substantially enclosed space, wherein the prism is provided in the liquid storage.
Furthermore, in order to attain the aforementioned second object, the liquid container according to the present invention has the following configuration.
More specifically, the present invention provides a liquid container attachable/detachable to/from a printing apparatus having optical means in which a light emission unit and a light receptor are fixed with a predetermined space, comprising: a liquid storage for reserving liquid; a liquid supply opening for supplying the liquid reserved in the liquid storage to an external; a first detection portion provided on a surface of the liquid storage, wherein when light is emitted, the first detection portion reflects different amounts of light depending on whether or not the liquid in the liquid storage exists; and a second detection portion provided in the neighborhood of the first detection portion, wherein when light is emitted, the second detection portion reflects a predetermined amount of light, wherein the container is movable relative to the optical means, and the predetermined amount of light reflected by the second detection portion is in between an amount of reflected light in a case where the first detection portion detects existence of liquid and an amount of reflected light in a case where the first detection portion detects non-existence of liquid.
Herein, it is preferable that the first detection portion is a light-transmitting prism provided on the bottom surface of the liquid storage, and the second detection portion is a concave curved surface portion provided on the external wall surface of the liquid container. In this case, it is preferable that a radius of curvature of the concave curved surface portion is larger in a first direction than a second direction, the first direction being parallel to a line connecting a light incident portion and light reflecting portion of the first detection portion, the second direction being perpendicular to the first direction.
Furthermore, it is preferable that the internal wall surface of the liquid container where the second detection portion is arranged has a rough surface. It is preferable that the liquid container further comprises a diffusion portion, provided in between the first detection portion and the second detection portion, for diffusing light reflected on the external wall surface of the liquid container, thereby preventing the light from returning to the light receptor. In this case, the second detection portion is a concave curved surface portion provided on the external wall surface of the liquid container, the diffusion portion is a rough surface formed integratedly on the external wall surface of the bottom surface of the liquid container, and an end portion of the concave curved surface portion is a part of a circular arc. It is preferable that the diffusion portion is further projected outwardly from the external wall surface of the container as compared to the first detection portion, or is situated on the same surface level.
Furthermore, in order to attain the aforementioned second object, the liquid-jet printing apparatus according to the present invention has the following configuration.
More specifically, the present invention provides a liquid-jet printing apparatus capable of including the liquid container having the above-described configuration, comprising: a carriage capable of holding the liquid container and scanning in the second direction; optical means, provided along a scanning path of the carriage, capable of emitting light to and the first and second detection portions of the liquid container and receiving reflected light; control means for controlling to drive the optical means while moving the liquid container by the carriage in the neighborhood of the optical means; and detection means for detecting existence/non-existence of liquid in the liquid container and/or existence/non-existence of the liquid container, based on the reflected light received by the optical means, wherein the light emission unit and light receptor of the optical means are arranged in the first direction.
Herein, it is preferable that the detection means comprises: maximum value detection means for respectively obtaining maximum values of an amount of received reflected light when a relative portion of the liquid container and the optical means are within respective predetermined ranges; comparison means for comparing the maximum values detected by the maximum value detection means with respective predetermined threshold values; and determination means for determining existence/non-existence of liquid in the liquid container and/or existence/non-existence of the liquid container, based on the comparison result obtained by the comparison means.
Furthermore, in order to attain the aforementioned third object, the liquid container according to the present invention has the following configuration.
More specifically, the present invention provides a liquid container comprising: a liquid storage for reserving liquid; a liquid supply opening for supplying the liquid reserved in the liquid storage to an external portion; a first detection portion provided on a surface of the liquid storage, wherein when light is emitted, the first detection portion reflects different amounts of light depending on whether or not liquid in the liquid storage exists; and a second detection portion provided in the neighborhood of the first detection portion, wherein when light is emitted, the second detection portion reflects a predetermined amount of light; and a diffusion portion, provided in between the first detection portion and the second detection portion, for diffusing light reflected on the external wall surface of the liquid container, thereby preventing the light from returning to an externally provided light receptor.
Herein, it is preferable that the first detection portion and the second detection portion are provided on the bottom surface of the liquid container.
Furthermore, it is preferable that the diffusion portion is further projected outwardly from the external wall surface of the container as compared to the first detection portion, or is situated on the same surface level.
Still further, it is preferable that the diffusion portion is a rough surface formed integratedly on the external wall surface of the bottom surface of the liquid container, or a concave portion formed on the external wall of the bottom surface of the liquid container.
Still further, the liquid container preferably further comprises: plural liquid storages capable of respectively reserving plural types of liquid; and plural prisms corresponding to the plural liquid storages, wherein a diffusion portion is provided in between the plural prisms.
Furthermore, in order to attain the aforementioned fourth object, the liquid-jet printing apparatus according to the present invention has the following configuration.
More specifically, the present invention provides a liquid-jet printing apparatus for performing printing by discharging liquid, comprising: a liquid container having a first detection portion and a second detection portion adjacent to the first detection portion, on at least one surface of the liquid container; a carriage capable of holding the liquid container and scanning along a direction in which the first and second detection portions are arranged; optical means, provided along a scanning path of the carriage, capable of emitting light to the first and second detection portions of the liquid container and receiving reflected light; control means for controlling to drive the optical means while moving the liquid container by the carriage in the neighborhood of the optical means; and detection means for detecting existence/non-existence of liquid in the liquid container and/or existence/non-existence of the liquid container, based on reflected light received by the optical means, wherein the detection means comprises: maximum value detection means for respectively obtaining maximum values of an amount of received reflected light when a relative portion of the liquid container and the optical means are within respective predetermined ranges; comparison means for comparing the maximum values detected by the maximum value detection means with respective predetermined threshold values; and determination means for determining existence/non-existence of liquid in the liquid container and/or existence/non-existence of the liquid container, based on the comparison result obtained by the comparison means.
Herein, it is preferable that the determination means first determines existence/non-existence of the liquid container, then determines existence/non-existence of liquid in the liquid container.
Moreover, it is preferable that the liquid-jet printing apparatus further comprises minimum value detection means for obtaining a minimum value of an amount of reflected light detected at a predetermined portion other than the first detection portion or the second detection portion, wherein the comparison means compares differences between the maximum values obtained by the maximum value detection means and the minimum value detected by the minimum value detection means, with predetermined threshold values respectively.
Herein, it is preferable that the liquid container comprises: a negative-pressure generating member accommodating chamber, having a liquid supply opening and an atmospheric-air communicating portion, for accommodating a negative-pressure-generating member; and a liquid storage, having a passage opening connected to the negative-pressure generating member accommodating chamber and forming a substantially enclosed space, wherein after the determination means in cooperation with the first detection portion detects existence/non-existence of liquid in the liquid container, a number of dots corresponding to liquid droplets discharged is counted and a request for exchanging the liquid container is displayed before consuming liquid in the negative-pressure generating member accommodating chamber.
Note that the prism employed in the present invention is formed with light-transmitting material, and has a surface constructing a part of the external wall surface of a container and plural reflection surfaces which are different from the foregoing surface. The reflection surfaces which contact with contents (e.g. ink) of the container have a predetermined angle with respect to a path of light. The prism is structured such that the amount of light, reflected on the surface constructing a part of the external wall of the container serving as an ink tank, is different depending on existence or non-existence of the contents in the container. In other words, the plural reflection surfaces are provided in the internal wall surface side of the container. Note that the plural reflection surfaces may be replaced with a curved surface. Moreover, the bottom surface portion of the prism is a surface which constructs a part of an external wall surface of the container.
Further, the diffusion portion indicates a portion for diffusing light reflected on the external wall surface of the container, thus preventing the light from returning to the light receptor.
Moreover, the concave polyhedral portion is a concave portion constituted with plural surfaces or a curved surface, provided on the surface (bottom surface portion) constructing a part of the external wall of the prism. In a case where the concave polyhedral portion is optically used, it serves as the aforementioned diffusion portion. The concave polyhedral portion has a concave shape when it is seen from the external wall surface of the container.
Furthermore, the ink-existence/non-existence detection portion (which is often referred to as a xe2x80x9cfirst detection portionxe2x80x9d in the summary) and ink-tank-existence/non-existence detection portion (which is often referred to as a xe2x80x9csecond detection portionxe2x80x9d in the summary) respectively indicate a portion having the function for detecting existence/non-existence of ink, and a portion having the function for detecting existence/non-existence of an ink tank.
The invention is particularly advantageous since the detection system, liquid-jet printing apparatus and liquid container according to the present invention enables to improve the precision in detecting existence/non-existence of the liquid container or detecting existence/non-existence of liquid therein by reducing noise returned to the photoreceptor.
Moreover, according to the liquid container and liquid-jet printing apparatus according to the present invention, there is an advantage in that the detection of existence/non-existence of a liquid container is accurately discriminated from the detection of a liquid level (or existence/non-existence of liquid) in the container when these are detected by a single sensor. Furthermore, even if the S/N (signal/noise) ratio is somewhat low, the present invention enables to detect existence/non-existence of a liquid container and a liquid level in the container.
Other objects and advantages besides those discussed above shall be apparent to those skilled in the art from the description of a preferred embodiment of the invention which follows. In the description, reference is made to accompanying drawings, which form a part thereof, and which illustrate an example of the invention. Such example, however, is not exhaustive of the various embodiments of the invention, and therefore reference is made to the claims which follows the description for determining the scope of the invention. dr
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the description, serve to explain the principles of the invention.
FIG. 1 is a perspective view showing a schematic construction of a printing apparatus, as a typical embodiment of the present invention, which includes a printhead for performing printing in accordance with an ink-jet printing method;
FIG. 2 is a block diagram showing the structure of a control circuit of the printing apparatus;
FIGS. 3A and 3B are perspective views showing an external appearance of a head holder 205 holding the ink tank 7 and a printhead 1;
FIG. 4 is a sectional side view showing an internal structure of the ink tank 7;
FIGS. 5A to 5C are illustration showing the structure of the ink tank 7 according to the first embodiment;
FIGS. 6A and 6B are explanatory views and FIG. 6C is a graph, showing the relative position relation between the ink tank 7 and an optical unit 14, and the relation between their relative positions and an amount of light received by a photoreceptor 16;
FIGS. 7A and 7B are block diagrams showing the detailed structure of an ink-existence/ink-tank-existence detection unit 25;
FIG. 8 is a flowchart showing control for detecting existence/non-existence of ink and existence/non-existence of an ink tank;
FIGS. 9A and 9B are explanatory views showing the structure of an optical prism 180 provided on the bottom surface of the ink tank 7;
FIGS. 10A to 10C are explanatory views showing the reflection surface on the bottom portion of the ink tank 7;
FIG. 11 is an explanatory view showing the reflection surface on the bottom portion of the ink tank 7;
FIGS. 12A to 12C are illustrations showing the structure of the ink tank 7 according to the second embodiment;
FIGS. 13A to 13C are explanatory views showing a concave curved surface reflection portion 190 seen from various directions, according to the second embodiment;
FIG. 14 is a cross section for explaining a concave polyhedral portion 200 of the optical prism 180 provided on the bottom portion of the ink tank;
FIG. 15 is a cross section for explaining a concave polyhedral portion 200 of the optical prism 180 provided on the bottom portion of the ink tank;
FIGS. 16A to 16C are explanatory views showing first and second modifications of a diffusion portion of the optical prism provided on the bottom portion of the ink tank;
FIG. 17 is an explanatory view showing a third modification of a diffusion portion of the optical prism provided on the bottom portion of the ink tank;
FIG. 18 is an explanatory view showing a modification of the optical prism provided on the bottom portion of the ink tank;
FIG. 19 is an explanatory view showing how light emitted by a light emission device 15 of an optical unit is reflected on the optical prism on the bottom surface of the ink tank and returned to a photoreceptor 16 of the optical unit;
FIGS. 20A and 20B are explanatory views showing a first modification of the optical prism according to the first embodiment;
FIGS. 21A and 21B are explanatory views showing a second modification of the optical prism according to the first embodiment;
FIGS. 22A and 22B are explanatory views showing a modification of the structure of the ink-tank-existence detection portion;
FIGS. 23A and 23B are explanatory views showing the structure of a conventional ink-tank-existence detection portion;
FIGS. 24A and 24B are explanatory views showing a modification of the diffusion portion;
FIGS. 25A and 25B are an explanatory view and a graph respectively showing the structure of the bottom portion of an ink tank containing plural colors of ink as a modification of the ink tank, and showing variations in the amount of light received by a photoreceptor 16;
FIGS. 26A and 26B are explanatory views and FIG. 26C is a graph, showing the relative position relation between the ink tank 7 and an optical unit 14, and the relation between their relative positions and an amount of light received by a photoreceptor 16;
FIG. 27 is a flowchart showing a modification of control for detecting existence/non-existence of ink and existence/non-existence of an ink tank; and
FIG. 28 is a graph showing variations in the amount of received light reflected on the ink tank shown in FIG. 9.